Electronic iginition circuit

ABSTRACT

AN ELECTRONIC IGNITION CIRCUIT IN WHICH AN ELECTRIC PULSE PRODUCED BY A MAGNETIC PICKUP DISTRIBUTOR IS UTILIZED TO   TRIGGER A POWER CIRCUIT TO CHARGE AND FREE AN IGNITION COIL.

United States Patent Charles Richard Harrow Sayreville, NJ.

Oct. 29, 1968 June 28, 1971 Solitron Devices, Inc. Tappan, N.Y.

Inventor Appl. No. Filed Patented Assignee ELECTRONIC IGNITION CIRCUIT 2Claims, 3 Drawing Figs.

US. Cl 123/148E, 315/209 Int. Cl F02p 3/02 Field of Search 123/148 (B),148 (E), 148 (DC), 148 (AC); 315/209,209

[51' I 21vn| 3RD I 4 STAGE ISTAGE] SIAGE I STAGE l I References CitedUNITED 5/1966 Konopa STATES PATENTS ort et a1.

hneider et a1.

1/1968 Kasama et a1 Primary Examiner- Laurence M. GoodridgeAtt0rneyBernard Malina, Esq.

l23/l48E l23/I48E 123/148E 123/148E ABSTRACT: An electronic ignitioncircuit in which an electric pulse produced by a magnetic pickupdistributor is utilized to trigger a power circuit to charge and fire anignition coil.

5T1! STAGE TO I lll' SBUIKPLUGS PATENTEDJUH28 I97] SHEET 1 BF 3 I ul wmu fi w J w N NN QM mn II R N I w. m W FM mfi mam Q 1 mm .5 MN kw J Q maNT, w Q QM mm v. M N n ,k R Q .MPIITLTIFIIRPIIII INVENTOR. CHARLESRICHARD HARROW ATTORNEY ELECTRONIC IGNITION CIRCUIT BACKGROUND OF THEINVENTION 1. Field of the Invention The invention relates to ignitionsystems for internal combustion engines and more particularly totransistorized ignition systems for internal combustion engines.

2. Description of the Prior Art Various types of transistorized ignitionsystems have been proposed in the past. One of the difficulties has beenassuring that the ignition coil was charged at the proper time.Excitation was provided by breaker points which required preciseadjustment. Further they were subject to wear and pitting by arcingduring the opening of the points. The present invention provides meansfor insuring the charge to the ignition coil at the proper time andreplaces the movable points with stationary coils.

SUMMARY An electronic ignition system in which an electric pulse from amagnetic pickup distributor is rectified, regulated and amplified totrigger a power circuit to energize and fire an ignition coil.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a schematic diagram of asystem embodying the invention.

FIG. 2 is a schematic diagram of a modification of the embodiment ofFIG. 1.

FIG. 3 is a schematic diagram of a further embodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to FIG. 1 of thedrawings, a magnetic pickup distributor 1 includes a PM rotor 2 and aplurality of pickup coils 3. While six pickup coils have beenillustrated and described, it is understood that the number will be thatof the number of cylinders of the internal combustion engine on which itis to be used. The magnetic pickup distributor is connected to be drivenby the engine in synchronism with a distributor 4 as indicated by'adashed line. The distributor 4 includes a movable contact 5 andstationary contacts 6 which connect to spark plugs (not shown).

The pickup coils 3 have one side connected by conductor 7 to ground andthe other sides are connected by conductor 8 to a diode 9 in the firststage of the ignition circuit. The diode 9 is connected by resistor 10and conductor 11 to base 12 of a transistor 13. The transistor 13 has anemitter 14 connected by resistor 15 and conductor 16 to a conductor 17which is connected by resistor 18 and conductor 19 to one side of abattery 20. Also the transistor 13 has a collector 21 connected byresistor 22 and conductor 23 to conductor 24 which is connected toground. A Zener diode 25 is connected by conductor 26 between theconductors 17 and 24. A resistor 27 is connected between the conductorsl1 and 17. A resistor 28 is connected between the conductors 11 and 24as is a capacitor 29.

The collector 21 of the transistor 13 is also connected by conductor 30to base 31 of a transistor 32 in the second stage of the ignitioncircuit. The transistor 32 has an emitter 33 connected by resistor 34 tothe conductor 24 and a collector 35 connected by resistor 36 to theconductor 17. Also the collector 35 is connected by conductor 37 to base38 of a transistor 39 in the third stage. The transistor 39 includes anemitter 40 connected by conductor 41 to emitter 42 of a transistor 43.Collector 44 of transistor 39 is connected by conductor 45 and resistor46 to the conductor 17. Also the collector 44 is connected by resistor47 to base 48 of the transistor 43. A diode 49 is connected between theconductor 41 and the conductor 24. The transistor 43 has a collector 50connected by 'resistor 51 to the conductor 17 and its base 48 isconnected by resistor 52 to the conductor 24.

A transistor 53 in stage 4 has a base 54 connected by diode 55 to thecollector 44 of the transistor 39. The transistor 53 has an emitter 56connected by a diode 57 and resistor 58 to the conductor 24. A resistor57A is connected across the diode 57. The transistor 53 also has acollector 59 connected by resistor 60 to the conductor 19 and alsoconnected by resistor 61 to base 62 of a transistor 63. The transistor63 includes an emitter connected by conductor 64 to the conductor 19 anda collector 65 connected by conductor 66 to base 67 of a transistor 68in stage 5.

A Zener diode 69 is connected between the conductor 66 and the conductor19. Also a resistor 70 is connected between the conductor 66 and 19. Thetransistor 68 has an emitter 71 connected to the conductor 19 by aresistor 72 and a collector 73 connected to base 74 of a transistor 75.The transistor 75 has an emitter 76 connected to base 77 of a transistor78 and also is connected by resistor 79 to the conductor 24. Also thetransistor 75 has a collector 80 connected to collector 81 of thetransistor 78 and the collectors 80 and 81 are connected by conductor 82to the conductor 19. Emitter 83 of the transistor 78 is connected byresistor 84 to the conductor 24 and is also connected to base 85 of atransistor 86 in the output stage.

The transistor 86 has a collector 87 connected by resistor 88 to theconductor 19 and an emitter 89 connected by conductor 90 to base 91 of atransistor 92. Also the emitter 89 is connected by resistor 93 to theconductor 24 and also by resistor 94 to the base 67 of the transistor68. Diodes 95 are connected between the conductors 90 and 24 and diode96 is also connected between the conductors 90 and 24 with the polarityopposite of .that of the diodes 95. The transistor 92 has an emitter 97connected by resistor 98 to the conductor 24 and a collector 99connected to one side of primary winding 100 of an ignition coil 101.The other side of the winding 100 is connected to conductor 19. Acapacitor 102 is connected across the winding 100.

The ignition coil 10] has a secondary winding 103 one side of which iscommon to the primary 100. The other side of the winding 103 isconnected by conductor 104 to the movable contact 5.

In the operation, the electric pulse produced by the magnetic pickupdistributor 1, which is synchronized with the distributor 4 to providethe pulse at the proper time, is rectified and amplified by the firsttwo stages of the circuit. The rising portion of the electric pulsefires the third stage, Schmitt trigger circuitry, which turns on theother stages to charge the ignition coil. The falling portion of thepulse resets the Schmitt trigger which turns off the output and thusdischarges the coil through the distributor to a predetermined sparkplug. The first three stages are regulated to a predetermined voltage bythe Zener diode 25, for example in a l2 volt system to 3.9 volts.

The fourth stage acts as a level shifter and switch for the fifth stageregulator circuitry. This stage limits the drive current to the outputtransistor 92 and enables it to operate in its active region. Thiseliminates the need for a voltage dropping ballast resistor. The outputstage turns on the output transistor 92 to connect the battery 20 tocharge the ignition coil and also provides protective circuitry thatenables the output transistor 92 to discharge the ignition coil withoutfailure. The capacitor 102 tunes the primary winding of the ignitioncoil and provides a capacitive load for the output transistor 92.

Reference is now made to FIG. 2 of the drawing, wherein like parts havebeen assigned the same reference numerals as in FIG. 1, in which thefirst stage has been modified from that shown in FIG. 1. A magneticpickup distributor has one side of a winding 3 connected by a resistor105 to the conductor 17. The other side of the winding 3 is connected byresistor 106 and conductor 107 to base 12 of a transistor 13. Acapacitor 29 is connected between the conductor 17 and the conductor [07and a resistor 108 is connected between the conductor 107 and conductor24. The transistor 13 has an emitter 14 connected to the conductor 17.Also the transistor 13 has a collector 21 connected by resistors 109 and22 and conductor 23 to the conductor 24. The junction point between theresistors 28 and 109 is connected by conductor 30 to the base 31 oftransistor 32 in the second stage.

The remainder of the circuits are the same as described for I FIG. 1,hence a detailed description will be omitted to avoid duplicity. Thefirst stage has been modified to improve the overall performance of thecircuit. The input signal from the magnetic pickup 1 is now connectedbetween the positive supply voltage and the base of the first transistor13. This enables the first stage to be triggered off the negativeportion of the input signal, thus improve the ignition timingrequirement. The bias for the first stage has been adjusted for theaforenoted change. The remainder of the circuits operate as set forthfor FIG. 1.

Reference is now made to FIG. 3 which illustrates a different embodimentthat requires fewer components. A magnetic pickup 111 has a permanentmagnet rotor 112 and an output winding 113. One side ofthe winding 113is connected by conductor 114, resistor 115 and conductor 116 to thepositive side of a battery 117. The negative side of the battery 117 isconnected to ground. The other side of the winding 113 is connected byresistor 118 and conductor 119 to base 120 of a transistor 121. Acapacitor 122 is connected between the conductors 114 and 119. Thetransistor 121 has an emitter 123 connected to the conductor 114. Alsothe transistor 121 has a collector 124 connected by resistor 125 andconductor 126 to base 127 of a transistor 128 in stage two. A Zenerdiode 129 is connected by conductor 130 between the conductor 114 and aconductor 131 which is connected to ground.

The transistor 128 has an emitter 132 which is connected by conductor133 to the conductor 131. A collector 134 of the transistor 128 isconnected by resistor 135 to the conductor 114. Also the collector 134of the transistor 128 is connected to base 136 ofa transistor 137. Thetransistor 137 has a collector 138 connected by a resistor 139 to theconductor 114. The transistor 137 has an emitter 140 connected byresistors 141 and 142 to the conductor 131. The junction point betweenthe resistors 141 and 142 is connected by conductor 143 and resistor 144to the conductor 126.

The emitter 140 of the transistor 137 is also connected by resistor 145to base 146 of transistor 147 in the third stage. The transistor 147 hasan emitter 148 connected by diodes 149 and 150 to the conductor 131 andalso a collector 151 connected by resistor 152 to the conductor 116.

The collector 151 of the transistor 147 is also connected by conductor153 to base 154 of a transistor 155 in the fourth stage. The transistor155 has an emitter 156 connected by resistor 157 to the conductor 131and a collector 158 connected by conductor 159 to the conductor 116.Also the emitter 156 of the transistor 155 is connected to base 160 of atransistor 161 which has a collector 162 connected to the conductor 159.The transistor 161 has an emitter 163 connected by conductor 164 tocollector 165 of a transistor 166 in the fifth stage.

The transistor 166 has an emitter 167 connected by conductor 168 to theconductor 131 and also a base 169 connected by conductor 170 to emitter171 of a transistor 172 in the output stage. The emitter 171 is alsoconnected by resistor 173 to the conductor 131. A resistor 174 isconnected between the conductor 164 and the conductor 131 as is a diode175. The transistor 172 has a base 176 connected by the conductor 164the distributor, and is triggered to the collector 165 of the transistor166. Also the transistor 172 has a collector 177 connected by conductor178 to one side of primary winding 179 of ignition coil 180. The otherside of the primary winding 179 is connected by conductor 181 to theconductor 116. The coil 180 has a secondary winding 182, one end beingin common with the primary winding 179 and the other end connected to adistributor. A capacitor 183 is connected across the primary winding179.

In the operation, the first stage senses the input signal produced bythe magnetic pickup, which is synchronized with by the negatively goingportion of this signal. The capacitor 22 furnishes t e necessaryfrequency compensation to provide stability. The signal from the firststage in turn triggers the two stage saturating amplifier of the secondstage. The Zener diode 129 regulates the voltage, for example to 6.2volts, and the resistor 115 limits the current. The switching levels ofthe second stage are shifted by the third stage transistor network, theoutput of which supplies the drive current for the fourth stage whichdrives the output transistor to charge the primary of the ignition coil.The fifth stage transistor limits the charging current to apredetermined value, for example 5 amps, by bypassing the base drive tothe output transistor when the predetermined level is reached. Thecapacitor 183 tunes the primary of the ignition coil and presents acapacitive load line for the output transistor. The diode protects theemitter-base junction of the output transistor 172 against any reversebias.

Although several embodiments of the invention have been illustrated anddescribed, various changes in the form and relative arrangement of theparts which will now appear to those skilled in the art, may be madewithout departing from,

the scope of the invention.

lclaim:

1. An electronic ignition circuit comprising an ignition coil having aprimary and a secondary winding, a distributor connecting said secondarywinding to loads in a predetermined sequence, a magnetic pickupsynchronized with said distributor for producing a signal atpredetermined times, a switching transistor connecting said battery tothe primary winding of said ignition coil, and circuit means responsiveto said signal from said magnetic pickup to actuate said switching meansto charge said ignition coil, said switching transistor being actuatedto charge said ignition coil by the rising portion of said signal, andactuated to discharge said ignition coil upon the falling portion ofsaid signal, including means for limiting the charging current throughsaid ignition coil, said limiting means comprising a resistor connectedto the emitter of said switching transistor for detecting said chargingcurrent and feedback means operative in response to said detected charg-

